Studies have been conducted on a technology (hereinafter, referred to as smart mirror) of combining a mirror and a display to show weather, schedule, or health information when a user is in front of the mirror. The smart mirror is a device into which a one-way mirror, having a characteristic of looking transparent only in one direction, and a display panel are integrated. The smart mirror functions as a mirror when the display panel on the rear surface of the one-way mirror is turned off, and provides a display function, with panel-emitted light passing through the one-way mirror when the display panel is turned on.